TKZ-Y, axial check valves (including subsea), 2″–84″, ASME 150–2500 / API up to 15 000

Description

TKZ-Y are axial check valves that the manufacturer offers in place of swing check valves (including those with controlled closing), dual-plate and piston check valves. The main task is to protect compressors and pumps from reverse flow. The valves are installed on the discharge of compressors of trunk gas pipelines, in compressor lines of LNG plants, in cooling water systems of ethylene and LNG production, in multiphase pumping systems, and on subsea pumps and flowlines.

All of the manufacturer's valves work on the Axial Flow principle, in use since 1955: the streamlined symmetrical annular channel between the inner and outer body has no sharp turns of the flow. The Total Velocity Management® concept controls the velocity of the medium in all zones and eliminates local high velocities, the main cause of noise, erosion and vibration. The full flow area and high pressure recovery in the body with a Venturi profile give very low pressure losses, and therefore lower operating costs for compression and pumping. The low static pressure in the throat creates a differential across the disc, so the valve opens easily and works stably as the flow changes.

The spring-assisted design gives ultra-fast non-slam closing with practically no reverse flow and no water hammer. For systems with several parallel compressors or pumps and for LNG lines this is critical. The low opening pressure is achieved by a large disc with the same effective area on both sides and improves the stability of the compressor system during start-up. Tight closing is provided by a metal-to-metal seal with line contact, which is not affected by erosion and deformation, unlike soft seals. The pressure drop and dynamic behaviour of the valve are predicted with high accuracy from full-scale test bench results and a mathematical model created jointly with a hydraulic laboratory. The internal design is based on simple mechanical principles, so the valve needs no maintenance.

Sizes range from 2″ to 84″, pressure classes ASME 150–2500 or API 3000–10 000, higher on request. The valve is designed for the customer's conditions, and fire-safe, cryogenic and subsea versions are available. The subsea axial check valve is made in sizes 2″–24″, classes ASME 150–2500 or API 3000–15 000, for depths up to 5000 m, with welded ends, hubs or flanges and optional qualification to API 6A PSL3(G) and/or PR2. It is used to protect subsea compressors and pumps and to separate interconnected injection and production lines.

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